In general, a fan motor assembly is commonly used for a vacuum cleaner that sucks to remove debris such as dust by using a suction force generated according to an operation of a driving motor.
The fan motor assembly includes a driving motor, a rotary fan engaged with a rotary shaft of the driving motor, an air guide member mounted between the driving motor and the rotary fan and guiding air toward the driving motor, and a cover that covers the rotary fan and the air guide member.
In a related art fan motor assembly for a vacuum cleaner, when a rotary fan is rotated fast by the driving motor to suck air, dust is collected in a dust collecting chamber, and air which has passed through the dust collecting chamber is exhausted to outside of a case, thereby performing cleaning. In this process, air distributively exhausted to an edge of the rotary fan is sent to the driving motor by a plurality of vanes formed at a guide member, cooling the driving motor, and then exhausted to outside of the case.
In an air guide member 1 of the related art fan motor assembly, as shown in FIG. 1, while sucked air is being guided or induced toward the driving motor (not shown), air has a viscous frictional force over a surface of a return vane 2, a boundary layer 3 is commonly formed on the surface of the return vane 2.
The boundary layer 3 increases a flow resistance of air blown to the driving motor, resulting in that air cannot smoothly guided toward the driving motor. Herein, the velocity of air flow indicated by an arrow becomes slow as it becomes closer to the surface of the return vane 2.
Accordingly, the amount of air guided to the driving motor, namely, the amount of air blown to the driving motor, is considerably reduced, degrading cooling efficiency of the driving motor, and a vacuum cleaner having such a fan motor assembly cannot have a good cleaning performance.